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Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Shell structure of the neutron-rich isotopes $$^{69,71,73}$$Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

The structures of the neutron-rich $$^{69,71,73}$$Co isotopes were investigated via ($$p,2p$$) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Level schemes were reconstructed using the $$gamma-gamma$$ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations suggests coexistence of spherical and deformed shapes at low excitation energies in the $$^{69,71,73}$$Co isotopes.

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:2 Percentile:25.8(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

 Times Cited Count:5 Percentile:16.24(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Activities on the leakage of radioactive substances from buried pipe with cracking

Kameyama, Yasuhiko; Yanai, Tomohiro; Kurosawa, Akihiko; Asano, Norikazu; Hiyama, Kazuhisa; Kusunoki, Hidehiko; Fukasaku, Akitomi

JAEA-Review 2011-017, 19 Pages, 2011/06

JAEA-Review-2011-017.pdf:2.8MB

The Japan Materials Testing Reactor (JMTR) is a testing reactor dedicated to the irradiation tests of materials and fuels. The JMTR has been in a shutdown period since 2006 for its refurbishment, and will restart in 2011. Water analysis and so on are carried out in the hot experimental room, and sample preparation and measurement for the radiation management are carried out in the radiation control room. The waste fluid such as hand-wash water, sample water, washing water generated in these rooms is transferred to the waste tank in the hot machine room through the buried pipe. The crack was found at the flange of the buried pipe when sewerage works were carried out. The flange is located in a non-controlled area. A small amount of radionuclide (cesium 137 and cobalt 60) was detected as a result of radioactivity measurement from the surrounding soil. In this report, the cause of the leakage from the buried pipe, the countermeasure and the prevention measure are summarized.

JAEA Reports

The Outline of investigation on integrity of JMTR concrete structures, cooling system and utility facilities

Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.

JAEA-Technology 2009-030, 165 Pages, 2009/07

JAEA-Technology-2009-030.pdf:69.18MB

The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.

Journal Articles

Alignment of cavities and magnets at J-PARC linac

Morishita, Takatoshi; Ao, Hiroyuki; Asano, Hiroyuki; Ito, Takashi; Ueno, Akira; Okawa, Tomohiro; Hasegawa, Kazuo; Ikegami, Masanori*; Naito, Fujio*; Tanaka, Hirokazu*; et al.

Proceedings of 10th International Workshop on Accelerator Alignment (IWAA 2008) (Internet), 6 Pages, 2008/02

It has been widely accepted that an accurate alignment is essential to achieve high beam quality and highly stable operation increasingly demanded in recent particle accelerators. The J-PARC linac components are finely aligned based on the precise survey network, where we have emphasized on attaining the smoothness between adjacent elements. A floor elevation of the accelerator tunnel has been periodically measured since the completion of the linac building to correct the error by the settlement. The alignment of the linac components have been finished at Sep. 2006 and the beam commissioning has been started at Nov. 2006. After a coarse adjustment of the RF phase and amplitude, nearly complete beam transmission was easily established without using steering magnet. This successful beam transport proves the validity of the alignment strategy and the accurateness of the alignment procedure.

Journal Articles

A Practical method for monitoring $$^{129}$$I concentration in airborne release

Koarashi, Jun; Akiyama, Kiyomitsu; Asano, Tomohiro; Kobayashi, Hirohide

Journal of Radioanalytical and Nuclear Chemistry, 267(1), p.155 - 159, 2006/01

 Times Cited Count:2 Percentile:80.59(Chemistry, Analytical)

To establish a practical method for monitoring$$^{129}$$I concentration in airborne release from the Tokai reprocessing plant,$$^{129}$$I collecting performance of sampling media used in the method was tested by in situ experiments. The results indicated that the combinational use of an activated charcoal-impregnated filter paper and an activated charcoal cartridge gives the collection efficiency of more than 90% for one-week sampling of real airborne effluent at sampling flow rates of 40.6-75.0 l min-1. The sampling and measurement conditions suitable for a routine-based monitoring were demonstrated taking into account the findings.

Journal Articles

Determination of chemical forms of $$^{3}$$H released to the atmosphere from the Tokai Reprocessing Plant

Koarashi, Jun; Mikami, Satoshi; Akiyama, Kiyomitsu; Asano, Tomohiro

Journal of Radioanalytical and Nuclear Chemistry, 262(3), p.569 - 572, 2005/01

A method using a system with two sampling units was proposed to determine the chemical forms of tritium released into the atmosphere from the Tokai Reprocessing Plant (TRP). The main advantage of the method is that no carrier gas is required for sampling in the case that air to be sampled has high specific activity of tritiated hydrogen (HT). Obserbations using this method showed that 19.1-28.3% of totak airborne tritium was released as HT from the TRP during reprocessing operation. No clear relationship was found between the ratios of HT release and the types of spent fuels reprocessed.

Journal Articles

Incorporating Tritiated Water into a $$^{14}$$C-Sampling System for Quantitative Estimation of$$^{14}$$C Activity in Airborne Effluent

Koarashi, Jun; Akiyama, Kiyomitsu; Asano, Tomohiro; Yokota, Tomokazu*

Journal of Radioanalytical and Nuclear Chemistry, 262(3), p.771 - 774, 2005/01

Effect of incorporating tritiated water into a $$^{14}$$C sampling system on sample preparation and $$^{14}$$C activity measurement by liquid scintillation counting were investigated. Experiments derived the limit of water content in prepared sample, and also demonstrated that $$^{14}$$C activity can be determined without any interference from$$^{3}$$H contamination for clear-solution sample. The results enabled us to estimate permissible reelative humidity of air required for accomplishing sample preparation and $$^{14}$$C activity measurement. These showed that for sampling of air with less than the permissible relative humidity, total $$^{14}$$C activity in airborne effluent can be evaluated accurately with no dehumidification of air.

Journal Articles

Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest

Koarashi, Jun; Iida, Takao*; Asano, Tomohiro

Journal of Environmental Radioactivity, 79(2), p.137 - 156, 2005/00

 Times Cited Count:14 Percentile:64.78(Environmental Sciences)

To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon (14C) abundances of chemically soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of 14C abundances showed that bomb-derived 14C has been penetrated into the first 16 cm mineral soil at least, whereas a significant amount of it has been still preserved as the acid-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived 14C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15 % of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter can not provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales.

Journal Articles

Chemical Composition of$$^{14}$$C in Airborne Release from the Tokai Reprocessing Plant, Japan

Koarashi, Jun; Akiyama, Kiyomitsu; Asano, Tomohiro; Kobayashi, Hirohide

Radiation Protection Dosimetry, 114(4), p.551 - 555, 2005/00

 Times Cited Count:17 Percentile:23.05(Environmental Sciences)

Fuel reprocessing plant is one of the most important sources of anthropogenic$$^{14}$$C in the environment. A method was developed to determine the amount and chemical composition of airborne $$^{14}$$C release from the Tokai reprocessing plant, Japan. Effluent monitoring using the method showed most of the $$^{14}$$C is released in CO$$_{2}$$ form and the ratio of $$^{14}$$C in hydrocarbons to the total is less than 3%, not depending on the type of fuel reprocessed. This evaluation would provide improved information on dynamical behavior of $$^{14}$$C in the environment and assessment of radioecological impact from nuclear fuel cycle.

JAEA Reports

Methods and Their Performances for Collecting Tritium, Carbon-14 and Radioiodine in Airborne Effluent from Tokai Reprocessing Plant

Koarashi, Jun; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Isaka, Keisuke*; Akiyama, Kiyomitsu; Asano, Tomohiro

JNC-TN8410 2004-003, 49 Pages, 2004/07

JNC-TN8410-2004-003.pdf:1.45MB

Radioactive airborne effluent discharged from Tokai reprocessing plant (TRP) contains tritium, carbon-14 and radioiodine. These radionuclides are collected with appropriate methods, respectively, in stacks to monitor their concentrations and discharged amounts. This report describes (1) the methods for collecting these radionuclides in TRP; (2) evaluations of the concentrations and discharged amounts; and (3) investigations on estimating performances of the collecting methods. The investigations showed that the collecting methods used in TRP have collecting efficiencies of more than 90% for tritium and radioiodine, and almost 100% for carbon-14. Considerations concerning collection of radionuclides in airborne effluent, made in this study, provided some technical aspects required for establishing more reliable monitoring systems.

Journal Articles

Evaluation of$$^{14}$$C Abundance in Soil Respiration using Accelerator Mass Spectrometry

Koarashi, Jun; Iida, Takao*; Moriizumi, Jun*; Asano, Tomohiro

Journal of Environmental Radioactivity, 75(2), 117 Pages, 2004/00

 Times Cited Count:5 Percentile:86.92(Environmental Sciences)

None

Journal Articles

Soil Carbon Dynamics Inferred from Carbon Isotope Compositions of Soil Organic Matter and Soil Respiration

Koarashi, Jun; Iida, Takao*; Moriizumi, Jun*; Asano, Tomohiro

Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.92 - 99, 2003/10

Soil organic matter (SOM) is a significant carbon reservoir in terrestrial ecosystems. Therefore, knowledge of SOM dynamics is essential for better understanding not only the global carbon cycle but also the environmental behabior of additional 14C produced by the nuclear power industry. In this study, carbon isotope compositions were determiend for chemically fractionated SOM and soil respiration in an urban forest, to investigate the formation, storage and decomposition of SOM.

JAEA Reports

Annual Report on Activities of Radiation Protection Division at JNC Tokai Works in Fiscal Year of 2002

Shinohara, Kunihiko; Asano, Tomohiro; Momose, Takumaro; Takeishi, Minoru; Kobayashi, Hirohide; Oka, Tsutomu; Takasaki, Koji

JNC-TN8440 2003-020, 125 Pages, 2003/09

JNC-TN8440-2003-020.pdf:11.14MB

This annual report summarizes the activities of the Radiation Protection Division at JNC Tokai Works in fiscal 2002.The Tokai Works undertakes various research and development for the reprocessing of spent fuel, plutonium fuel fabrication, fast reactor fuel recycling technology, and radioactive waste treatment and disposal, all of which are done under strict safety management.The major radiation facilities in the Tokai Works are the Tokai Reprocessing Plant (TRP), which has been in operation since 1977, three MOX fuel fabrication facilities, the first of which has been in operation since 1965, the Chemical Processing Facility (CPF) where fast reactor (FR) reprocessing technologies are being developed, and various other radioisotope and uranium research laboratories.The Radiation Protection Division is responsible for radiation control in and around these facilities, including personnel monitoring, workplace monitoring, consultation on radiological work planning and evaluation, monitoring of gas and liquid waste effluents, environmental monitoring, instrumentation, calibration, quality assurance, and safety research. The Division also provides technical support and cooperation to other international and domestic institutes in the radiation protection field.In fiscal 2002, the results of radiological monitoring showed the situation to be normal, and no radiological incident or accident occurred. The maximum annual effective dose to radiation workers was 6.5 mSv and the mean annual effective dose was 0.1 mSv. Individual doses were kept within the annual dose limit specified in the safety regulations. The estimated effective dose caused by gas and liquid effluents from the TRP to members of the public around the Tokai Works was 4.2 * 10$$^{-4}$$mSv. Environmental monitoring and effluent control were performed appropriately in compliance with safety regulation and standards.

JAEA Reports

Partial replacement of JMTR beryllium frame

Kaminaga, Katsuo; Tsuboi, Kazuaki; Kusunoki, Hidehiko; Asano, Norikazu; Yanai, Tomohiro

JAERI-Tech 2003-051, 26 Pages, 2003/05

JAERI-Tech-2003-051.pdf:2.67MB

The sixth replacement of beryllium frame has been accomplished for the west and north frame, while the old east frame of fifth generation is preserved for use. JMTR achieved its first criticality in 1968 and has been in operation until today, with an integrated thermal output of 141.454.5 MWd. During that period replacement was carried out 4 times for all the frames, east, west and north. This time, differently from the previous replacement, west and north frames only were manufactured and installed, when the old east frame was left for continuous use, based on the past experience. Such a strategy contributed to reduction of budget and the waste associated.

Journal Articles

Construction and commissioning of a 215-m-long beamline at SPring-8

Goto, Shunji*; Takeshita, Kunikazu*; Suzuki, Yoshio*; Ohashi, Haruhiko*; Asano, Yoshihiro; Kimura, Hiroaki*; Matsushita, Tomohiro*; Yagi, Naoto*; Isshiki, M.*; Yamazaki, H.*; et al.

Nuclear Instruments and Methods in Physics Research A, 467-468(Part1), p.682 - 685, 2001/07

no abstracts in English

Journal Articles

Construction and commissioning of a 215-m-long beamline at SPring-8

Goto, Shunji*; Takeshita, Kunikazu*; Suzuki, Yoshio*; Ohashi, Haruhiko*; Asano, Yoshihiro; Kimura, Hiroaki*; Matsushita, Tomohiro*; Yagi, Naoto*; Isshiki, Maiko*; Yamazaki, H.*; et al.

Nuclear Instruments and Methods in Physics Research A, 467-468(Part1), p.682 - 685, 2001/07

 Times Cited Count:120 Percentile:0.88(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

None

; Asano, Tomohiro; *

PNC-TN7420 92-018, 53 Pages, 1992/06

PNC-TN7420-92-018.pdf:1.4MB

None

51 (Records 1-20 displayed on this page)